Micro-mirror and a method for fabricating the same

ABSTRACT

A micro-mirror for deflecting an incident light is disclosed, wherein the micro-mirror comprises: a mirror section for reflecting an incident light issued from a laser diode; a hinge section including a fixed section and a movable section each having a flat surface; and a drive section having a bi-morph structure made of two or more of materials having different heat expansion coefficient for deflecting said mirror section to change relative angle to said incident light.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Priority Document No.2001-065070, filed on Mar. 8, 2001 with the Japanese Patent Office,which document is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a micro-mirror applied to a MEMS (MicroElectro Mechanical Systems) and a method for fabricating suchmicro-mirror, and particularly this invention relates to a micro-mirrorsuitable for document scanning application and a method for fabricatingthe same.

2. Description of the Related Art

A micro-mirror (namely, a scanning mirror) is fabricated by a micromachining using a silicon substrate as a part applied to a laserscanner, for example. In a conventional micro-mirror such as describedin an article [Technical Digest of the 16^(th) Sensor Symposium, 1998pp. 167-170], for example, a flat surface section of a silicon substrateis made to be a mirror surface in almost of all the micro-mirrors. Inthis case, on an upper substrate made of silicon, a micro-mirror and ahinge section for supporting the micro-mirror on the upper the substrateare fabricated by an-isotropic etching process, and the micro-mirrorvibrates by an electro-static power acting between an electrode formedon a lower substrate and an electrode provided on the upper substrate ina direction perpendicular to the upper substrate with the hinge sectionas a center.

Incidentally, the conventional micro-mirror as described above hasadvantages such that a fabricating process is simple because of itssimple construction. On the contrary, as the flat surface of thesubstrate is directly utilized, its deflection angle is limited to acertain limited extent, so that a scanning area or extent is restrictedwhen used as a scanner. Conventionally, it is proposed to provide aslant surface on a substrate and a scanning mirror is set on the slantsurface as a scanner (U.S. Pat. No. 5,966,230 or Japanese Laid-openPublication H7-199,103). In this article, the scanner is used as abar-code reader, and in this case, the slant surface having an angle of45 degrees relative to the flat section is at first formed on thesubstrate, and then the scanning mirror supported by an intolerancehinge section is provided at the slant surface, thereby the scanningmirror is made rotatable by an electro-static power with the intolerancehinge section as a center.

But in a particular application such as the bar-code reader, it isrequested to be able to scan a target moving to all directions, toaccept any shape of the target, to perform a high speed scanning of thetarget moving in a short time, etc. so that it is desired to enlarge thedeflection angle of the micro-mirror. In the above-mentioned scanner, adeflecting direction of the scanning mirror is also substantiallyperpendicular to the top surface of the slant surface, and the rotationangle thereof is limited thereby.

Further in the conventional micro-mirror, the hinge section isfabricated by forming an aperture by etching, but generally, defects arefrequently generated at corners of the aperture, so that if the apertureis formed only within a single surface (crystalline plane) asconventional, it causes a problem where the hinge section is tend to bedestroyed by the concentration of the stress at the defect section upondriving. Further, there exists another problem where a dimensionalaccuracy of the hinge section is largely degraded by over-etching uponforming the aperture.

SUMMARY OF THE INVENTION

This invention is done to overcome the above-mentioned, and one aspectof the present invention is to propose a micro-mirror capable ofperforming high speed and wide scanning. Further it is another aspect ofthe present invention to propose a method for easily fabricating amicro-mirror capable of performing high speed and wide scanning bysimple fabricating processes.

The micro-mirror of the present invention comprises a mirror sectionequipped with a reflecting film, and a drive means having a bi-morphstructure utilized the difference of thermal expansion coefficient in atleast two original materials, wherein the drive means changes therelative angles of the mirror section relative to the incident light.The drive means practically comprises a first drive film provided at onesurface of the hinge section and a second drive film provided at anothersurface of the hinge section and the second drive film has largerthermal expansion coefficient than the first drive film. Both firstdrive film and the second drive film are conductive and may be made fromdifferent material to each other, and may have different conductivity toeach other. For example, the first drive film is made from poly-crystalsilicon including an impurity such as phosphor (P) and the second drivefilm is made from aluminum film.

In this micro-mirror, the movable section of the hinge section havingthe bi-morph structure deflects by supplying current to the first drivefilm, and thereby the incident light is deflected along with the changeof relative angle of the mirror section to the incident light inaccordance with the deflection of the movable section. As the mirrorsection is formed to be a cantilever beam structure that comprises thefixed section of the hinge section as a fixed end, and the mirrorsection as a free end, the mirror section as the free end can get largerdeflection angle.

Further according to a method for fabricating a micro-mirror of thepresent invention, the fabrication process includes concrete processesfor a micro-mirror that comprises: a mirror section for reflecting anincident light; a hinge section including a fixed section and a movablesection each having a flat surface; and a drive means having a bi-morphstructure made of two or more of materials of heat expansion coefficientfor deflecting a relative angle of the mirror section to the incidentlight, wherein the hinge section and the mirror section are integrallyconstructed by a structured film formed on a semiconductor substrate byutilizing crystal an-isotropy of the semiconductor substrate. With theseprocesses, the micro-mirror having a slant surface for the mirrorsection is easily fabricated.

According to the micro-mirror of the present invention, as the drivemeans of the mirror section having the reflective surface, the bi-morphstructure utilizing the differences in thermal expansion coefficient ofat least two materials are employed, so that it is possible to perform ahigh speed and wide angle deflection of the mirror section.

Particularly the micro-mirror of the present invention comprises: ahinge section including a fixed section and a movable section eachhaving a flat surface; and a drive means having a bi-morph structuremade of two or more of materials of heat coefficient for deflecting arelative angle of the mirror section to the incident light so that itbecomes possible to deflect the mirror section more widely. Accordingly,it becomes possible to make a scanning area wider when applied to alaser scanner or the like.

Further, according to a method for fabricating the micro-mirror of thepresent invention, the mirror section and the hinge section are formedby utilizing crystal anisotropy of a semiconductor substrate,particularly a silicon substrate for example, so that the micro-mirrorof this invention can be easily fabricated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a perspective view for showing one embodiment of a scannerstructure to which one embodiment of a micro-mirror of the presentinvention is applied;

FIG. 2 is a top view for explaining a structure of the micro-mirror inFIG. 1;

FIG. 3 is a bottom view for explaining the structure of the micro-mirrorin FIG. 1;

FIG. 4 is a side view for explaining operation of the micro-mirror inFIG. 1;

FIGS. 5A to 5D are sectional views for showing one embodiment of amethod for fabricating the micro-mirror in fabrication steps;

FIGS. 6A to 6C are sectional views for explaining the fabrication stepsfollowing the fabrication steps in FIGS. 5A to 5D;

FIGS. 7A and 7B are sectional views for explaining the fabrication stepsfollowing the fabrication steps in FIGS. 6A to 6C;

FIGS. 8A and 8S are sectional views for explaining the fabrication stepsfollowing the fabrication steps in FIGS. 7A to 7B; and

FIG. 9 is a top view for showing another embodiment of a structure ofthe micro-mirror in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, one of embodiments of the present invention will be explained withreference to the accompanying drawings. FIG. 1 shows a construction of alaser scanner (a bar-code scanner, for example) using a micro-mirror ofthe present invention, wherein a laser scanner 1 scans a bar-code with alaser beam irradiated from a laser diode 3 and converged at a micro-lens4 by deflecting the laser beam with a micro-mirror 16, then, itsreflected light (a return beam) is detected by a photo diode 5. Thesemicro-mirror 10 and the photo diode 5 are fabricated using a commonsilicon substrate 11 as will be described later.

The micro-mirror 10 is opposite to the laser diode 3, and has a mirrorsection 12 having a slant surface and a flat-shaped hinge section 13where the mirror section 12 side is a free end and the hinge section 13side is a fixed end. For example, the hinge section 13 is formed to havea near V-shaped form for positioning a triangle aperture 14 in-between,and comprises a movable section 13A linking to the mirror section 12 anda fixed section 13B formed on a flat surface (100) of a siliconsubstrate 11 by extending the movable section 13A. Namely thismicro-mirror 10 is constructed to be a cantilever boom structure wherethe mirror section 12 at a tip rotationally deflects around a boundarysection between the fixed section 13B and the movable section 13A of thehinge section 13.

These mirror section 12 and the hinge section 13 are, as described laterin the fabrication method, so formed that, at first, a silicon nitridefilm is formed, as a structured film, on a front surface of the siliconsubstrate 11 on which a slant surface (111) is formed by an-isotropicetching, then they are integrally fabricated by restoring the thin filmof the silicon nitride by removing the silicon substrate 11 in anetching process.

The mirror section 12 is formed by utilizing the slant surface (111)obtained by performing an-isotropic etching to the silicon substrate 11.An angle formed by the flat surface (100) and the slant surface (111) ofthe silicon substrate 11 is 55 degrees, so that the mirror section 12 isslanted by about 55 degrees relative to the fixed section 13B of thehinge section 13. Accordingly, it becomes possible to obtain a widerangle formed by the mirror section 12 and the fixed section 13B.Incidentally, as shown in FIG. 2, a reflection film 12A made of analuminum film, for example, having high reflection coefficient isprovided at the mirror section 12.

FIG. 2 is a top view of the micro-mirror 10 in FIG. 1, and FIG. 3 is abottom view thereof. As shown in FIG. 2, a poly-silicon film 15including an impurity such as phosphor (P), for example, is formed on afront surface from the moving section 13A to the fixed section 13B ofthe hinge section 13. On the contrary, as shown in FIG. 3, an aluminumfilm 16 is entirely formed on a back surface of the moving section 13Aof the hinge section 13. Thereby the poly-crystal silicon film 15 andthe aluminum film 16 are formed to be a bi-morph structure whilesandwiching the hinge section 13 made of the silicon nitride. In thiscase, although not shown, an electrode pad (FIG. 7A) for supplyingcurrent to the poly-crystal silicon film 15 is provided on the fixedsection 13B of the hinge section 13.

In this micro-mirror 10, the laser light irradiated from the laser diode3 becomes outgoing laser light R1 by being reflected at the mirrorsection 12 after passing through the micro-lens 4 as shown in an initialstate designated in FIG. 4 by a real line. The outgoing laser right R1is scattered upon scanning the target, and its return light R2 isdetected by the photo diode 5.

Further when current is supplied the poly-crystal silicon film 15, thehinge section 13 is heated by Joule heat of the poly-crystal silicon,and as a result, both the poly-crystal silicon film 15 and the aluminumfilm 16 are thermally expanded. In this case, the thermal expansioncoefficient of the aluminum is about nine times larger than the thermalexpansion coefficient of the poly-crystal silicon, and accordingly themovable section 13A of the hinge section 13 bends to a directionindicated by an arrow A as shown in FIG. 4 with dotted line around aboundary section of the fixed section 13B and the movable section 13A ofthe hinge section as a center, namely to a direction perpendicular tothe flat surface (100) of the silicon substrate 11 (upwards).

Generally it is well known that a deflection speed of a bi-morphstructure of a micron order in size is possible to be up to several kHz,and accordingly, a high-speed deflection of the hinge section 13 can beexpected. Responding to the deflection of the hinge section 13, themirror section 12 rotates around the boundary of the hinge section 13 asa center. In this case, the laser light issued from the laser diode 3 isreflected at the mirror section 12 and becomes an outgoing light R3. Asthe mirror section 12 has a large angle such as 55 degrees, so that themirror section 12 at the tip can obtain larger deflection angle.

As described above, by thermally driving the micro-mirror 19 having thebi-morph structure, the laser light issued from the laser diode 3 iscontinuously switched to two directions such as the outgoing light R1 ata halt mode and the outgoing light R3 at a drive mode, and is able toirradiate onto the bar-code 20 to scan. Further the hinge section 13having the flat shape deflects around the boundary section of fixedsection 13B and the movable section 3A as a center in a direction of thearrow A, thereby deflects in a direction perpendicular to the flatsurface (100) of the silicon substrate 11, then such deflection istransmitted to the mirror section 12 of the free end. Accordinglydifferent from the conventional structure, the structure is soconstructed that the gravity itself of the mirror section 12 moves, andtherefore the mirror section 12 can move more widely in the deflectionangle.

Further, in this embodiment, as performing a high speed deflection ofthe hinge section 13 having a bi-morph structure and forming the mirrorsection 12 as to have a large angle of 55 degrees relative to the hingesection 13, it becomes possible to deflect the laser light withrelatively high speed at the mirror section 12, so that it becomespossible to make larger the deflection angle.

FIG. 5 to FIG. 8 show a series of fabrication process of themicro-mirror of the present invention. In this method, a silicon nitridefilm (SiNx) is formed as a structured film on the silicon substrate 11which has the slant surface (111) formed by an-isotropic etching, andafter that the mirror section 12 and the hinge section 13 are formed byetching in order to remove the silicon substrate 11.

As shown in FIG. 5A, at first an n-type silicon substrate 11 of 200 μmin thickness is prepared. A thermal oxide film of 300 μm in thickness,for example, is formed on both surfaces of the silicon substrate 11,then the thermal oxide film is performed a patterning by etching usingphoto lithography and hydrogen fluorides (HF). Thus the thermal oxidefilm mask 21 for silicon wet an-isotropic etching is formed.

And, the wet an-isotropic etching by TMAH (Tetra-Methyl AmmoniumHydroxide) is performed using the thermal oxide film mask 21. In thiscase, the etching rate is 0.5 μm/min., for example. Thereby, grooves 22,23 are formed as shown in FIG. 5B. The groove 22 is 400 μm in width(mask size), 300 μm in length and 60 μm in depth, and the groove 23 is300 μm in width, 300 μm in length and 60 μm in depth.

Next, the thermal oxide film mask 21 on the back surface of the siliconsubstrate 11 is protected by a photo-resist (not shown) and only thethermal oxide film mask 21 on the front surface of the silicon substrate11 is removed. After that, a thermal oxide film of 300 nm in thicknessis again formed on the front surface of the silicon substrate 11,thereby a thermal oxide film mask 24 is formed by patterning thus formedthermal oxide film for second wet an-isotropic etching as shown in FIG.5C.

The patterning of the thermal oxide film mask 24 is performed by forminga photo-resist film (not known) having even thickness by spray methodusing a resist spray apparatus and exposing by an UV (Ultra Violet) rayirradiation with deep focal depth using a projection exposure apparatus.In this case, as the thermal oxide film mask 21 on the back surface ofthe silicon substrate 11 is protected by the photo-resist (not shown), apattern of the thermal oxide film mask 21 on the back surface of thesilicon substrate 11 is the same.

After that, as shown in FIG. 5D, the silicon substrate 11 is furtheretched by 60 μm by performing a wet an-isotropic etching by TMAH, forexample, using the thermal oxide film masks 21, 24. Thus grooves 25, 26of 120 μm in depth are formed. Thereby, the slant surface (111) forforming the mirror section 12 and the flat surface (100) for forming thehinge section 13 are formed. A width (mask size) of the groove 25 is 50μm, for example, and a width of the groove 26 is as same as that of thegroove 23.

Next, as shown in FIG. 6A, the thermal oxide films 21, 24 on bothsurfaces of the silicon substrate 11 are removed, and then siliconnitride films (SiNx) 27 of 200 nm in thickness are formed on bothsurfaces of the silicon substrate 11 by a low-pressure CVD (ChemicalVapor Deposition) method.

Then as shown in FIG. 6B, a phosphor (P) doped poly-crystal silicon film15 of 500 nm in thickness is formed on both surfaces of the siliconsubstrate 11 by the low-pressure CVD (Chemical Vapor Deposition) method.

Further after spraying photo-resist by a resist spray apparatus, aphoto-resist pattern is formed by a projection exposure apparatus, andthen performs patterning of the poly-crystal silicon film 15, as shownin FIG. 6C, by etching using SF6 (Sulfur Hexa-Fluoride) gas with thephoto-resist pattern as a mask. Thus the poly-crystal silicon film 15 isformed to be a shape as shown in FIG. 1 or FIG. 2. In this case, thepoly-crystal silicon film 15 on the back surface of the siliconsubstrate 11 is similarly removed by dry etching using SF6 gas.

Again, a photo-resist pattern (not shown) is formed by patterning usingthe projection exposure apparatus after spraying photo-resist by theresist spray apparatus, then the silicon nitride film 27 is performedthe patterning as shown in FIG. 6C, using the photo-resist pattern as amask, by dry-etching using CF4 (Carbon Tetra-Fluoride) gas. Thus, thesilicon substrate 11 is exposed at a part of the groove 25.

After that, an aluminum film of 200 nm in thickness is formed, forexample, by sputtering method. Further, a photo-resist pattern (notshown) is formed by patterning with the projection exposure apparatusafter photo-resist is sprayed by the resist spray apparatus, and thenthe aluminum film is patterned by the etching using phosphoric acid withthus formed photo-resist pattern as a mask. Thus as shown in FIG. 7A,the reflection film 12A of the mirror section 12 and the electrode pad28 for connecting to the poly-crystal silicon film 15.

Next as shown in FIG. 7B, a photo-resist pattern 29 is formed bypatterning with the projection exposure apparatus after spayingphoto-resist by the resist spray apparatus, then the nitride siliconfilm 27 is patterned by etching using the photo-resist pattern 29. Thusthe silicon substrate 11 is exposed at the groove 25 and the peripherythereof. In this case, the front surface of the silicon substrate 11 isprotected by the photo-resist.

And, as shown in FIG. 8A, by a deep RIE (Reactive Ion Etching) methodperforming silicon etching while generating high-density plasma byswitching C4F8 (Octafluorocyclobutane) gas and SF6 gas, a through hole30 is formed by etching the back surface of the silicon substrate 11 ata bottom section of the groove 25 and further the silicon substrate 11around the groove 26. Thus, the mirror section 12 made of the siliconnitride film 27 is cut off to be a free end and the movable section 13Aof the hinge section 13 made of the silicon nitride film 27 is formed.

Lastly, as shown in FIG. 8B, after the photo-resist pattern 29 isremoved, and an aluminum film 16 of 700 nm in thickness is formed onentire back surface of the silicon substrate 11 by sputtering method,for example. Thus the micro-mirror 10 of the present invention iscompleted.

In the micro-mirror 10 thus fabricated by this fabrication method, thenitride silicon film 27 formed by the low-pressure CVD method, forexample, is utilized as materials for the mirror section 12 and thehinge section 13, so that it is extremely tough to repeating vibrationwithout any stress such as normal metal material. As the thickness ofthe nitride silicon film 27 can be precisely controllable, themicro-mirror 10 having extremely preferable reproducibility in vibrationcharacteristics can be fabricated. The mirror section 12 has thereflection film 12A having a mirror surface formed by aluminumdeposition, so that a reflection coefficient is high. Further, themirror section 12 form large angle such as 55 degrees relative to thefixed section 13B of the hinge section 13, so that the mirror section 12can deflect more widely.

One example of the micro-mirror 10 fabricated by the fabrication methodas explained above is described next.

The completed micro-mirror 10 has a symmetric form in left and right andits size of D1, D2 and D3 in FIG. 2 are 80 μm, 120 μm and 80 μm,respectively. Further its size of D4, D5, D6 and D7 in FIG. 2 are 120μm, 80 μm, 140 μm and 80 μm, respectively. In addition in FIG. 2, itssize of D8 and D9 are 70 μm and 40 μm, respectively. In thismicro-mirror 10, when the vibration characteristics were measured byflowing pulse current to the poly-silicon film 15, the maximumdeflection angle was 25 degrees and the maximum deflection speed was 3kHz.

As described above, one embodiment of the present invention is explainedwith reference to accompanying drawings, but this invention is notlimited to this embodiment, and various modified forms are possible. Forexample, sizes of each section, materials of the substrate, thickness offilm and process conditions are freely modified without exceeding thepurpose of the present invention. For example, any of PotassiumHydroxide (KOH), Hydrazine, Ethylene-Diamine-Pyrocatechol Water (EPW) isusable instead of the TMAH.

In the above described embodiment, the micro-mirror 10 has one apertureand two hinge sections, but it is possible to align a plurality ofapertures in neighbor and to provide three or more than three hingesections. Further in the above mentioned embodiment, the fixed sectionof the hinge section is formed into two sections, but these are formedin integrated form as shown in FIG. 9.

Further in the above mentioned embodiment, the ply-crystal silicon filmand the aluminum film are formed at the hinge section made of siliconnitride as the bi-morph structure, but it is possible to use other filmmaterial such as a combination of poly-crystal silicon and Titanium (Ti)film. Further, it is possible to construct the bi-morph structure bypositioning the poly-crystal silicon films that comprises same typematerial but having different conductivity and having differentsectional areas as wiring on both surfaces of the hinge section. In thiscase, the heat value differs owing to the difference of theconductivity, namely resistance and as a result, the rates of thermalexpansion are different to each other, so that similar deflection can beobtained as if the bi-morph structure using different materials isemployed.

In addition, the laser scanner is explained as one example of thesemiconductor device in the above-described embodiment, but thisinvention can apply to a method for fabricating other semiconductordevices such as a sensor in the MEMS field and a DMD (DigitalMicro-mirror Device).

1. A micro-mirror for deflecting an incident light, comprising: a mirror section for reflecting an incident light at a relative angle; a hinge section including a fixed section and a movable section each having a flat surface; said mirror section and said hinge section being integrally formed such that said mirror section extends from said movable section of the hinge section and is formed slanted to said flat surface of the movable section of the hinge section; and a drive means having a bi-morph structure made of two or more of materials having different heat expansion coefficient for deflecting said mirror section to change the relative angle to said incident light.
 2. The micro-mirror of claim 1, said mirror section is slanted by approximately 55 degrees to said flat surface of the movable section of the hinge section.
 3. The micro-mirror of claim 1, wherein said drive means includes: a first drive film provided on one of surfaces of said moving section of the hinge section, and a second drive film provided on another of the surfaces of said moving section and having larger thermal coefficient than said first drive film.
 4. The micro-mirror of claim 3, wherein said first drive film and second drive film are made from different types of conductive materials to each other.
 5. The micro-mirror of claim 4, wherein said first drive film is a poly-crystal silicon film including impurities, and said second drive film is an aluminum film.
 6. The micro-mirror of claim 3, wherein said first drive film and second drive film are made from the same types of materials having different resistance to each other.
 7. The micro-mirror of claim 1, wherein said hinge section and said mirror section are integrally constructed on a structured film formed on a semiconductor substrate.
 8. The micro-mirror of claim 7, wherein said semiconductor substrate is a silicon substrate.
 9. The micro-mirror of claim 7, wherein said fixed section and movable section of the hinge section are formed on a first crystalline surface of a silicon substrate respectively, and said mirror section is formed on a second crystalline surface of said silicon substrate.
 10. The micro-mirror of claim 9, wherein said hinge section is fixed to said silicon substrate by said fixed section.
 11. The micro-mirror of claim 7, wherein said structured film includes a nitride film.
 12. The micro-mirror as cited in of claim 11, wherein said movable section and said mirror section of said hinge section are made only by a thin film of said nitride film.
 13. A scanner device comprising: a light emitting device; a mirror section for reflecting an input incident light from said light emitting device at a relative angle; a hinge section including a fixed section and a movable section each having a flat surface, said mirror section and said hinge section being integrally formed such that said mirror section extends from said movable section of the hinge section and is formed slanted to said flat surface of the movable section of the hinge section; and a micro-mirror equipped with a drive means having a bi-morph structure made of two or more of materials having different heat expansion coefficient for deflecting said mirror section to change the relative angle to said incident light; and an optical detector for detecting a return light of a light irradiated by reflecting at said mirror section.
 14. The scanner device of claim 13, wherein said hinge section and said mirror section are integrally constructed on a structured film formed on a semiconductor substrate; and said optical detector is formed on said silicon substrate.
 15. A method for fabricating a micro-mirror which comprises: a mirror section for reflecting an incident light at a relative angle; a hinge section including a fixed section and a movable section each having a flat surface; and a drive means having a bi-morph structure made of two or more of materials having different heat expansion coefficient for deflecting said mirror section of the relative angle to said incident light; wherein said hinge section and the mirror section are integrally constructed by a structured film formed on a semiconductor substrate by utilizing crystal anisotropy of said semiconductor substrate such that said mirror section extends from said movable section of the hinge section and is formed slanted to said flat surface of the movable section of the hinge section.
 16. The method for fabricating the micro-mirror of claim 15, wherein; said movable section of the hinge section is so formed as to be continuous from said fixed section of the hinge section and is formed so as to construct a bent slanting surface at an extended section of the fixed section of the hinge section.
 17. The method for fabricating the micro-mirror of claim 16, further comprising the steps of: forming a first groove having a first skewed surface at a side wall section on a front surface of said semiconductor substrate, and a second groove having a second skewed surface substantially parallel to said first skewed surface of the first groove at a position and opposite to a flat surface section around said first groove on a back surface of said semiconductor substrate; forming structured films at said first skewed surface of the first groove and said flat surface section around said first groove; forming a first drive film at one surface of said structured film; forming said mirror section and said hinge section made of the structured film by removing said semiconductor substrate with etching process after performing a through-hole etching of said semiconductor substrate to make one end of said structured film to be a free end at a bottom section of said first groove; and forming a second drive film on another surface of the structured film constructing said hinge section.
 18. The method for fabricating the micro-mirror of claim 17, wherein an-isotropic etching is performed to said first groove and said second groove after forming said first groove on the front surface of the semiconductor substrate and said second groove on the back surface of the semiconductor substrate.
 19. The method for fabricating the micro-mirror of claim 18, wherein said an-isotropic etching is performed using a mask formed by patterning a photo-resist film by UV ray projection exposure method, wherein said photo-resist film is uniformly formed in thickness by a spray method. 20.-26. (canceled) 